There have been a number of examples of instruments and methods for treating cancerous tumors. While these prior art methods and apparatus have been shown to partially or entirely eliminate cancerous tumors within a patient's tissue and thereby improve the patient's condition, unfortunately, none have proven to completely eliminate the cancerous cells in all cases, or to otherwise provide a complete cure. Further, many of these prior art methods will adversely impact healthy tissues and cells within the patient in addition to the cancerous cells. Thus, there is a need for improved methods and apparatus for treating cancerous tumors.